Power systems often include multiple circuit breakers used to protect and isolate individual branch circuits powered from a common buss. Such branch circuit breakers are used to protect equipment and wiring from the effects of overcurrent resulting from abnormal overload and short circuit conditions. In certain applications it is desirable or necessary to monitor the current of each branch circuit in order to determine the portion of total buss current drawn by each circuit.
Such current monitoring may be used to meter power consumption for billing purposes, preventive maintenance, load shedding or for other purposes. Power system designers often use off-the-shelf stand-alone current sensors in applications where current monitoring is required. These may take the form of current shunts, current transformers, Hall Effect sensors, or other varieties of variable sensors.
Stand-alone current sensors have certain disadvantages, including, for example, the complexity of additional wiring and the modification of standard circuit breakers to accommodate the current sensors.